What does definiens mean?
Definiens is a technical noun from formal logic and philosophy of language denoting the expression that does the defining within a definition. Every explicit definition can be split into two components: the definiendum, the term being defined, and the definiens, the words or symbols that supply its meaning. In the statement 'a square is a rectangle with four equal sides,' for example, the phrase after 'is' constitutes the definiens. Borrowed directly from Latin, where it means 'that which defines,' the word carries an academic register and appears chiefly in discussions of semantics, lexicography, and analytic philosophy. Its natural companion term is 'definiendum,' and the two are frequently mentioned together when logicians analyze whether a definition is clear, circular, or adequate. For anyone studying how meaning is constructed and communicated, 'definiens' offers a precise way to name the defining side of the equation.
nounThe word, phrase, or symbol that serves to define another expression; the defining part of a definition, as opposed to the term being defined (the definiendum).
- The expression (words, phrase, or symbols) used to define another term; contrasted with the definiendum.
"In the definition 'a bachelor is an unmarried man,' the phrase 'an unmarried man' is the definiens."
"In the definition 'a triangle is a polygon with three sides,' the phrase 'a polygon with three sides' functions as the definiens."
"Philosophers of language debate whether any verbal definiens can fully capture the meaning of certain primitive concepts."
The Latin-style plural 'definientia' is standard in formal logical and philosophical writing; 'definienses' is not used.
"Good definitions require definientia that are better understood than the terms they define."
Every definition has two parts, and 'definiens' is the half doing all the work — Latin for 'that which defines.'
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of definiens
Definiens comes directly from Latin, where it is the present participle of definire, meaning 'to define' or 'to set bounds to,' itself formed from de- ('down, completely') plus finire ('to limit, bound'), from finis ('boundary, end'). English adopted it as a technical term alongside its partner 'definiendum' (the passive participle, 'that which is to be defined'). It shares its root with related English words such as 'define,' 'definite,' and 'finite.'
How definiens is actually used
Definiens is a technical term confined almost entirely to formal logic, philosophy, linguistics, and lexicography. It is always paired conceptually with its counterpart 'definiendum.' The plural is 'definientia.'
Easily confused with definiens
The definiendum is the term being defined, while the definiens is the words that do the defining.